/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.tags.form;

import javax.servlet.jsp.JspException;

/**
 * Abstract base class to provide common methods for implementing
 * databinding-aware JSP tags for rendering a <i>single</i>
 * HTML '<code>input</code>' element with a '<code>type</code>'
 * of '<code>checkbox</code>' or '<code>radio</code>'.
 *
 * @author Juergen Hoeller
 * @since 2.5.2
 */
public abstract class AbstractSingleCheckedElementTag extends AbstractCheckedElementTag {

	/**
	 * The value of the '<code>value</code>' attribute.
	 */
	private Object value;

	/**
	 * The value of the '<code>label</code>' attribute.
	 */
	private Object label;


	/**
	 * Set the value of the '<code>value</code>' attribute.
	 * May be a runtime expression.
	 */
	public void setValue(Object value) {
		this.value = value;
	}

	/**
	 * Get the value of the '<code>value</code>' attribute.
	 */
	protected Object getValue() {
		return this.value;
	}

	/**
	 * Set the value of the '<code>label</code>' attribute.
	 * May be a runtime expression.
	 */
	public void setLabel(Object label) {
		this.label = label;
	}

	/**
	 * Get the value of the '<code>label</code>' attribute.
	 */
	protected Object getLabel() {
		return this.label;
	}


	/**
	 * Renders the '<code>input(radio)</code>' element with the configured
	 * {@link #setValue(Object) value}. Marks the element as checked if the
	 * value matches the {@link #getValue bound value}.
	 */
	@Override
	protected int writeTagContent(TagWriter tagWriter) throws JspException {
		tagWriter.startTag("input");
		String id = resolveId();
		writeOptionalAttribute(tagWriter, "id", id);
		writeOptionalAttribute(tagWriter, "name", getName());
		writeOptionalAttributes(tagWriter);
		writeTagDetails(tagWriter);
		tagWriter.endTag();

		Object resolvedLabel = evaluate("label", getLabel());
		if (resolvedLabel != null) {
			tagWriter.startTag("label");
			tagWriter.writeAttribute("for", id);
			tagWriter.appendValue(convertToDisplayString(resolvedLabel));
			tagWriter.endTag();
		}

		return SKIP_BODY;
	}

	/**
	 * Write the details for the given primary tag:
	 * i.e. special attributes and the tag's value.
	 */
	protected abstract void writeTagDetails(TagWriter tagWriter) throws JspException;

}
